Enantioselective synthesis of (-)-curcumanolide A using enzymatic transesterification of meso-spirodiol

meso-Spirodiol 12 and spirodiacetate 13 were stereoselectively prepared using pi-face selective Grignard addition to norbornanone 7. Asymmetric transesterification of meso-diol and hydrolysis of meso-diacetate were studied using lipases. Pseudomonas fluorescens lipase-catalyzed transesterification of meso-diol 12 afforded the monoacetate (-)-21 of high enantiomeric excess (>99% ee). The formal synthesis of(-)-curcumanolide A has been achieved from the optically active (-)-21.